Normally, bowel movement occurs habitually and dose not prevent someone from leading daily life. However, comfortable bowel movement of sufficient volume becomes difficult for some reasons and a condition associated with a physical suffering is caused. It is called constipation. Constipation is generally associated with straining during bowel movement, hard feces, decreased frequency of bowel movement, sensation of incomplete evacuation, bloating, prolonged transit time of food/stool in the entire gastrointestinal tract or colon and so on.
Constipation is classified into acute constipation and chronic constipation based on a period of medical history. In addition, constipation is classified into organic constipation and functional constipation based on its etiology. Organic constipation is a condition that it is difficult to defecate due to organic disorders such as stricture, obstruction and so on of gastrointestinal tract caused by colonic cancer, colonic polyps, uterine fibroid and so on. Furthermore, functional constipation is further classified into symptomatic constipation, drug-induced constipation and other constipation. Symptomatic constipation is constipation secondary to diseases other than gastrointestinal diseases. Drug-induced constipation is constipation which is secondarily caused by drugs, and it is known that it is caused by the administration of drugs which have an antimotility effect, such as opioid, anticholinergic drugs and the like. Functional constipation which is not symptomatic constipation or drug-induced constipation is the most common type, it is also called chronic idiopathic constipation (CIC), and it is caused by various reasons such as changes in eating habits and living environment, psychological factors and so on. Chronic constipation can be also classified into slow transit constipation and outlet obstruction based on reasons of constipation. Slow transit constipation is a condition in which the passage of the stool through the proximal colon to distal colon is impaired due to the decrease of colonic smooth muscle contraction, diminished peristalsis and the like, and outlet obstruction is a condition in which it is not possible to defecate due to impaired function of defecation even though the stool is transferred to rectum. Irritable bowel syndrome with constipation (IBS-C) is constipation in which gastrointestinal symptom dominated by abdominal pain, abdominal discomfort and stool abnormality is continued without organic changes in the gastrointestinal tract, and some patients of functional constipation may be classified as IBS-C (see Non-patent literatures 1-3).
The treatment of constipation includes life therapy, drug therapy, behavior therapy and surgical therapy. As the first choice in the treatment, life therapy involving a correction of irregular dietary habits, correction of bowel habits, and sufficient intake of high-fiber food and water is a basic treatment. Drug therapy is indicated in patients whose symptoms of constipation do not improve with life therapy.
In principle, drug therapy is initiated with drugs having a mild effect such as osmotic laxatives and bulk-forming laxatives which increase a volume of gut content. Irritant laxatives, prokinetic agents and the like are used when the effect of the above drugs is insufficient. Osmotic laxatives and bulk-forming laxatives are less addictive and can be administered for a long time. However, it is important to care for renal disorder, abnormal electrolyte level in the blood, hypermagnesemia of renal disorder or the like. In addition, it is known that addictions and inflammatory changes on intestinal mucosa may be caused by continued administration of irritant laxatives.
Lubiprostone is known as a new therapeutic agent for constipation (see Non-patent literature 4). Lubiprostone is sold as a therapeutic agent for chronic constipation (except for constipation due to organic diseases) in Japan. Lubiprostone is also sold as a therapeutic agent for chronic idiopathic constipation and irritable bowel syndrome with constipation, and is approved as a therapeutic agent for opioid-induced constipation (OIC) in the U.S.A.
Therefore, it is said that the drugs for the prevention or treatment of constipation are not sufficient now, and a drug for the prevention or treatment of constipation having a new mechanism of action, which causes fewer adverse reactions, has been strongly desired.
Compound 1 or a pharmaceutically acceptable salt thereof is known to be useful as an agent for the prevention or treatment of a disease associated with hyperglycemia such as diabetes, abnormal glucose tolerance, impaired fasting glucose, diabetic complication, obesity and so on (see Patent literatures 1-3).
However, it is not known that Compound 1 or a pharmaceutically acceptable salt thereof is useful as an agent for the prevention or treatment of constipation.    Patent literature 1: International publication No. WO2004/018491    Patent literature 2: International publication No. WO2009/084531    Patent literature 3: International publication No. WO2009/128421    Non-patent literature 1: Tetsuji Kitahora and 4 persons, Bessatsu Nippon Rinsho Shinryouikibetsusyoukougun series, 2009, Vol. 12, p. 422-427    Non-patent literature 2: Kouji Komori and 4 persons, Bessatsu Nippon Rinsho Shinryouikibetsusyoukougun series, 2009, Vol. 12, p. 433-435    Non-patent literature 3: George F. Longstreth et al, Gastroenterology, 2006, Vol. 130, p. 1480-1491    Non-patent literature 4: S. Fukudo et al, Neurogastroenterology and Motility, 2011, Vol. 23, p. 544-e205